There is need in the medical field for equipment which will rapidly produce clear plastic plates containing a plurality of pockets for carrying out various chemical reactions. In practice, body fluids are injected into the pockets which contain various chemicals and the color of the reaction between these chemicals and the body fluid is read to determine various body conditions. The plates with pockets and passageways therein may be molded of clear plastic with little difficultly. However, it is essential that a clear plastic cover be laid down over the faces of each plate to completely enclose the pockets in the plate. Obviously the clear plastic must be very precisely laid down in a wrinkle free condition so that the color chemical reactions in the pockets of the plate may be accurately read through the cover. Heretofore a clear plastic tape having adhesive on one face thereof has been used to provide covers for each side of the plastic plate.
A prior art method and machine, described in greater detail in the detailed description of the preferred embodiment section of the application, utilized a hexagonal wheel having an adhesive laminate strip on some of the sides thereof. The laminate was applied to the plate in a stamping motion. The adhesive laminate was fed to the hexagonal wheel at the first location, was cut into strips at a second location after the wheel had indexed, and was applied to the plate at a third location by moving the plate upwardly to contact the wheel positioned thereabove. The plate was then turned over and the process repeated for the other side. With this particular machine operating at its best speed, approximately twenty-five plate sides can be done per minute.
The aforedescribed machine had a number of disadvantages. Besides being relatively slow, and besides causing wrinkles or trapped air bubbles in the second laminate application step, the aforedescribed machine also had problems with accurately locating the laminate and the plate. Often, the machine would not be properly adjusted and would apply too much pressure to the plate. In addition, the prior art machine used a vacuum to hold the laminate to the wheel as it indexed around. The hexagonal wheel was comprised of blocks of tool steel having bores drilled therethrough so that the vacuum could be applied to the periphery of the wheel. This resulted in a non-uniform vacuum being applied across the face of the adhesive laminate. Consequently, the laminate sometimes slipped, could not be properly and accurately held in position, and was prone to becoming wrinkled.
While the prior art machine produced generally acceptable results to plates that were evaluated or read manually, it did not produce a sufficiently satisfactory product that could be read by a computer. The air bubbles and wrinkles, oftentimes minute, often produced incorrect readings by the computer.